Improvement in slate-frames



UNITED Simfree PATENT `DAVID GUMMING, JR., 0F NEW YORK, NQY.

IMPROVEMENT IN SLA'i'E-FRAlVlES.

peciication forniirg part of Letters Patent No. 58,225, dated September 535, 1866; antedated i September 17, 1866.

To all whom it may concern:

Be it. known that I, DAVID CUMMING, J r., of the city, county, and State of New York, have invented a new and usel'ul Improvement in Slate-Prairies and in frames for other purposes; and l do hereby declare that the following is a t'ull, clear, and exact description of theinvention and the mode of constructing said improved frames, reference being had to the annexed drawings, making a part of this specification, in which- Figure 1 is a t'ront view Fig. 2, a transverse section 5 Fig. 3, a section of one otl the corners 5 and Fig. 4 shows one ot' the corners taken apart;

The same letters refer to corresponding parts in the diti'erent figures, in which A is the slate; B,the frame. G C C C are continual screws, passing diagonally through the corners ofthe frame, for the purpose ot' holding the joints ot' the frame together.

The frame is put together by being placed around theslate in the usual manner, and titted at the corners with a tongue and groove or other device, and held together by glue or other means. Holes are then bored diagonally across the corners to receive the continuous screws, which are inserted, and the ends eut oit' smooth withtheframe.

y The ends of the screw at G are left on to show how the screws are put in. This makes the joint so strong that the edges ot' the frame can be rounded and better finished than the square edges.

The advantages of using the continuous screw are that the thread has a hold upon the wood its Whole length, and it can be cut off smoothly with the frame, thereby admitting of a better finish. The ordinary wood-screw may be used 5 but I prefer the continuons screw for the above reasons.

Vhat I claim as new, and desire to secure by Letters Patent, is

A slate frame when constructed with a miterjoint having a tongue and groove, or similar device, and held "together by means ot' a continuous screw, substantially as set forth.

DAVID CUMMING, I R.

Witnesses:

CHARLES I. SMITH, J. HENRY WILKINs. 

